Attachment of ³¹Cl and ³⁹Cl induced by high-energy neutrons to coexisted aerosols

In order to confirm the effects of physicochemical properties such as liquid or solid of coexisted aerosol on radioactive aerosol formation, the number size and activity size distributions of ³⁸C1 and ³⁹C1 aerosols (just use Cl aerosols to protect confusion) generated by irradiation of argon (Ar) gas containing liquid dioctyl-phthalate (DOP) or solid NaCl aerosols with 45 MeV quasi-monoenergetic neutrons were measured. In the case of DOP aerosol, the ³⁸C1 and ³⁹C1 respectively formed from the (n, 2np) and (n, np) reactions of ⁴⁰Ar were observed. It was found that the activity size distribution curve shifted toward larger particle diameter, compared to the number size distribution. The measured activity size distribution of Cl aerosols was in good agreement with the calculated activity size distribution assuming the surface attachment of ³⁸C1 and ³⁹C1 to DOP aerosol. In the case of NaCl aerosol, the Cl aerosol formation could be also explained by the same attachment model in the case of DOP. These findings suggest that the formation mechanism of Cl aerosols is not affected by the physicochemical properties such as liquid or solid coexisted aerosols.